In recent years, various techniques have been disclosed as a technique for obtaining a measurement error as a geomagnetic sensor of a magnetic sensor. For example, a technique is disclosed in which registration information in which a measurement position is associated with depression of geomagnetism is prepared as a database, and, when the measurement position and the depression of geomagnetism as actual measured information are acquired, it is judged whether or not a measurement error as the geomagnetic sensor falls within a normal range based on a comparison result of the registration information and the actual measured information (see, for example, Patent Literature 1)